1. Field of the Invention
This invention relates to techniques for treating urinary strictures.
2. Related Art
A stricture is an abnormally narrowed segment of an otherwise patent biological tube or conduit, such as the gastrointestinal tract, genito-urinary tract, pulmonary system, vascular system, or other systems in the body. Strictures may occur at various places within these systems in the body, such as in or near a blood vessel, the bronchial tree, the colon, a gastrointestinal body structure, a genital body structure, a kidney, a post-operative stricture, a pulmonary body structure, the rectum, or the sphincter, or a urethral body structure. The degree of narrowing, the length, and the significance of the stricture may differ greatly between particular strictures, and is responsive to the nature of the conduit which is subject to the stricture. Various etiological factors might be responsible for the development or exacerbation of any particular stricture; these may include, for example, infection, inflammation, trauma (whether external, internal, or iatrogenic or other surgical trauma), or cancer. One or more of these factors causes the lumen of the affected conduit to narrow, that is, to stricture, with consequential obstruction of the lumen and compromise of the function of the conduit.
Treatment of strictures is aimed at restoration of intraluminal patency and physiological function. Because of the presence of abnormal or diseased tissue at the stricture, surgical treatment by endoscopic or by open surgical techniques often poses extra difficulties and has significant morbidity. Moreover, because the tissue of the stricture wall is already diseased, it often generates further scarring and fibrosis when it heals after surgery, which can lead to recurrence of the stricture.
Accordingly, it would be advantageous to provide a method and system for treatment of strictures, such as for example urinary strictures, which use existing tissue, which promote healing of existing tissue, and which help to prevent recurrence of the stricture. This advantage is achieved in an embodiment of the invention in which a supporting frame, such as a cylindrical collagen frame with a diameter comparable to the normal lumen, is disposed intraluminally in a constricted region of the stricture, energy is emitted to ablate and harden the collagen and the tissue, and the supporting frame is used to maintain patency of the lumen and to prevent reformation of the stricture during a healing period.
The invention provides a method and system for treatment of body strictures to restore luminal diameter to within a normal diameter range, in which the stricture is dilated to stretch its lumen to a desired diameter, collagen is exuded near to existing tissue of the stricture so as to be absorbed by that tissue or adhere to that tissue, making a collagen-enhanced tissue structure, and energy is emitted to affect the collagen-enhanced tissue, such as by ablation or by hardening. Ablation and hardening may be repeated so as to create a set of layers of hardened collagen in the form of a supporting frame, preferably having a hollow cylindrical shape.
In a preferred embodiment, dilation of the stricture is achieved by expanding one or more balloons, or by the pressure of exuded collagen, until the stricture is larger than a normal diameter range. When energy is emitted into the collagen, the stricture contracts back to the normal diameter range, either by ablation of excess tissue or by plating of the stricture wall.
In a preferred embodiment, the stricture""s tissue is also isolated by a set of balloons at either or both ends of the stricture, so as to isolate the stricture and restrict the collagen to the stricture""s tissue.
In a preferred embodiment, the stricture""s tissue is also supported by a stent, which is preferably tack-welded onto the stricture""s tissue using collagen. Collagen adheres to the stent, which supports the stricture""s tissue until the stent is absorbed into that tissue.